const input = document.getElementById('input')
// let timer = null
// input.addEventListener('keyup', function (e) {
//   if (timer) {
//     clearTimeout(timer)
//   }
//   timer = setTimeout(() => {
//     console.log(e.target.value)
//     timer = null
//   }, 500)
// })

// 防抖
function debounce (fn ,delay = 500) {
  let timer = null
  return function () {
    if (timer) {
      clearTimeout(timer)
    }
    timer = setTimeout( () => {
      fn.apply(this, arguments)
    }, delay)
  }
}
input.addEventListener('keyup', debounce(function(){
  console.log(this.value)
}, 1000))